Characterization of T-DNA insertion mutants in terms of fatty acid composition and plant phenotype.

Fatty acid biosynthesis 2 (FAB2) is an essential enzyme responsible for the synthesis of unsaturated fatty acids in chloroplast membrane lipids found in leaves and triacylglycerols (TAG) in seeds. FAB2 functions at the junction of saturated to unsaturated fatty acid conversion in chloroplasts by converting 18:0-ACP to 18:1-ACP. In the present study, plant growth and seed phenotypes were examined in three Arabidopsis T-DNA mutants (, , and ). The three T-DNA mutants exhibited increased 18:0 fatty acid content in both the leaves and seeds. The degree of growth inhibition of the mutant was proportional to the increase in 18:0 and decrease in 18:3 fatty acids present in the leaves. The mutation affected seed yield but not the seed phenotype. This result indicates that FAB2 affects the fatty acid composition of the leaf chloroplast membrane more than seed TAG. In summary, the characteristics of these three mutants provide information for studying leaf membrane lipid and seed oil biosynthesis.